Analysis of divergent transcripts in estrogen-dependent signaling. - Project Summary The endocrine hormone estrogen (E2) actions by binding to its estrogen-receptor alpha (ERα), stimulates a robust mitogenic response in ER+ cells. In this regard, signal-regulated divergent transcription and its products have emerged as an important class of molecules that regulate various endocrine pathways such as estrogen and androgen signaling. Recent studies suggest that divergent transcripts are cell- and tissue-specifically expressed, and the E2-regulated divergent transcription is critical to eliciting full E2-driven gene expression. E2 signaling triggers a highly coordinated transcriptional program, leading to a robust mitogenic response that drives different cellular activities. Understanding the molecular mechanisms through which divergent transcription or transcripts regulate E2-responsive, ERα-dependent transcription will increase our understanding of the diseases caused by aberrant E2-signaling. Deciphering the molecular mechanisms of action of divergent transcripts in ER+ cells will be very important. In the preliminary study involving cellular and genomic approaches, E2- regulated divergent RNAs were identified and annotated. In addition, the initial characterization of a novel E2- regulated divergent transcript suggests that it controls E2-driven cellular processes and gene expression. In the current proposal, the molecular mechanisms by which divergent transcripts regulate E2-dependent signaling will be determined. The overarching hypothesis is that specific biochemical and structural properties of divergent transcripts underlie their ability to control critical E2-dependent pathways. A complementary set of biochemical, molecular, cell-based, proteomic, and genomic assays will be used to study the molecular mechanisms by which divergent transcript regulates E2-dependent transcription and growth of ER+ cells: specifically (1) Aim 1 will determine the molecular mechanisms of action of E2-regulated divergent transcript, in E2-dependent signaling, and (2) Aim 2 will identify the mechanism by which divergent transcripts control the assembly of E2-dependent gene regulatory complex. Successful completion of these aims will yield a new understanding of how divergent transcripts control key E2-dependent cellular pathways.
